Cambodian police on Thursday rescued 99 Thai workers tricked and forced into working illegally in Phnom Penh where they were held in a building by a Chinese gang.

The rescue operation was carried out by Cambodian authorities, Thai police and Royal Thai Embassy officials.

Officials surrounded the building which was being guarded by almost 50 Chinese. Officials were able to capture almost 40 of them and rescue all the Thais from the building at 5pm.

A source said that most of the victims were tricked by other Thais recruiting people for well-paying jobs such as online gambling promotions and online marketing in Cambodia. One victim told police they learned about the jobs via Facebook.

A gang of traffickers allegedly led the victims across the border illegally and then transported them to Phnom Penh by van. When they arrived at the building, they were locked up and forced to sign a contract.

The victims received a salary only for the first month. Those who refused to work were assaulted, handcuffed or left starving for two days, according to one of the victims. All of them were also reportedly forced to lure other Thais to work for the same operation or invest with them.

So far, police are expanding their investigation in the hope of saving other victims. Police believe there could be hundreds more.

Police have further warned Thais wanting to apply for well-paying jobs abroad to check with the Labour Ministry to avoid becoming a victim of human trafficking.